What could be the problem in Macbook Air 13?

Question

macOS

Hello.
There was a problem in Macbook air 13. The bottom line is a sharp decrease in RAM.
I turn on the mac, everything goes fine for a couple of minutes, but then the RAM drops sharply from 2.5 GB to several tens of MB (I judge the decrease by CleanMyMac).
Then the total freeze begins, you have to close all programs, clean the RAM, and so on - a vicious circle.
What I just didn’t do: I deleted all the programs in order to check if it was some kind of program that eats so much, but no, even without running any programs, the picture does not change, yesterday Sierra was completely installed again.
All unsuccessful. :(
On the Internet, I did not find such precedents. Mac without various influences from outside, the authorized service did not reveal any defects in hardware.

Answer 1

Let's start with a simple one:
1. The Mac has always worked like this: everything that you can potentially run is stored in RAM to speed up the launch of the application, but there should not be strong freezes from this;
2. Do not forget that you have old hardware for such a modern OS, there will be minor freezes - disable a number of unnecessary functions;
3. I hope after installing a clean system you did not install CleanMyMac, but looked at the problem with the RAM through the System Monitor or the console;
4. If you installed CleanMyMac, then remove it. You will see the result immediately, for example, when logging into the system, the mouse and keyboard will no longer freeze.